Adeno-associated virus (AAV)-based gene therapy is gaining popularity owing to its excellent safety profile and effective therapeutic outcomes in a number of diseases. Intravenous (IV) injection of AAV into the tail vein, facial vein and retro-orbital (RO) venous sinus have all been useful strategies to infuse the viral vector systemically. However, tail vein injection is technically challenging in juvenile mice, and injection at young ages (≤ postnatal day-(P)21) is essentially impossible. The temporal or facial vein is localized anterior to the ear bud and is markedly visible in the first couple of days postnatally. However, this method is age-dependent and requires a dissecting microscope. Retro-orbital injection (ROI), on the other hand, is suitable for all murine ages, including newborn and older mice, and is relatively less stressful to animals compared to tail vein injection. Although many reports have shown ROI as an effective route of AAV delivery, herein we aim to highlight and summarize the methods and benefits of ROI. To capture the full spectrum of transduction efficiency mediated by ROI, we transduced the editing-dependent reporter mice (Ai9 Cre reporter mice) with the AAV9 vector, which targets a wide range of peripheral tissues with exceptional brain tropism. We also provide a comprehensive description of the ROI technique to facilitate viral vector administration without complications.
Inherent plasticity and various survival cues allow glioblastoma stem-like cells (GSCs) to survive and proliferate under intrinsic and extrinsic stress conditions. Here, we report that GSCs depend on the adaptive activation of ER stress and subsequent activation of lipogenesis and particularly stearoyl CoA desaturase (SCD1), which promotes ER homeostasis, cytoprotection, and tumor initiation. Pharmacological targeting of SCD1 is particularly toxic due to the accumulation of saturated fatty acids, which exacerbates ER stress, triggers apoptosis, impairs RAD51-mediated DNA repair, and achieves a remarkable therapeutic outcome with 25%-100% cure rate in xenograft mouse models. Mechanistically, divergent cell fates under varying levels of ER stress are primarily controlled by the ER sensor IRE1, which either promotes SCD1 transcriptional activation or converts to apoptotic signaling when SCD1 activity is impaired. Taken together, the dependence of GSCs on fatty acid desaturation presents an exploitable vulnerability to target glioblastoma.